1. Field of the Invention
The invention relates to a roller skate comprising a frame, means for fixing said frame to a person""s foot, and at least two balls, which are freely rotatably supported by concave rollers, whose axes of rotation extend in a direction, transversely to the longitudinal direction of the frame and in use parallel to a rolling surface.
2. Discussion of the Background
With a similar roller skate, which is known from US patent U.S. Pat. No. 4,076,263, each ball is supported by one roller positioned vertically above said ball and two rollers positioned in front of and behind the central roller respectively. Said rollers are concave. The roller skate is supported on the road surface by means of said balls, whereby the presence of the balls leads to an improved road behaviour in comparison with that obtained with conventional axle-supported, barrel-shaped rollers which roll on the road surface. In particular when braking, said balls exhibit better road behaviour, because the balls can also rotate i-n a direction transversely to the direction of transport. The concave rollers thereby exert a force on the balls, as a result of which the balls are gradually brought to a standstill. One drawback of the known roller skate is the fact that, due to the presence of the relatively large rollers on either side of the balls, the number of balls to be mounted under the frame is limited. This has an adverse effect on the rolling behaviour of the roller skate.
The object of the invention is to provide a roller skate wherein the balls can be positioned a relatively small distance apart.
This objective is accomplished with the roller skate according to the invention in that a roller is present between two balls which are arranged side by side in the longitudinal direction of the frame, which roller bears against both balls during operation.
The diameter of the roller can be selected practically independently of the distance between the two balls which are arranged side by side, so that an optimum freedom of design is obtained.
Another embodiment of the roller skate according to the invention is characterized in that the number of rollers less the number of balls equals 1.
Since the number of rollers is only 1 higher than the number of balls, a relatively simple and inexpensive construction of the roller skate is obtained.